function isWeixin() {
    var ua = window.navigator.userAgent;
    if ((ua.match(
        /(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i
    ))) {
        // window.location.href="mobile.html"
    } else {
        window.location.href="index.html"
        // iphbottom_text
    }
}
isWeixin()
let downloadApp =()=>{
    // window.location.href=" http://app.xiaomi.com/detail/793914"
}